Basic hydrogen peroxide (BHP) is a principle fuel used in the operation of chemical oxygen-iodine lasers (COIL). COIL lasers are short wavelength high-power chemical lasers with wide ranging industrial, technological, and military applications. COIL lasers, which are electronic transitional lasers, are favored over vibrational or rotational transition lasers because they have one of the best beam qualities of any available laser, which allows for clean cuts and welds, as well as simple splitting and direction. In addition, the COIL laser has greater scalability than photolytic and solid state devices.
BHP is generated by the combination of alkali hydroxide, typically potassium hydroxide, with hydrogen peroxide according to the formula:OH−+H2O2+M+→O2H−+H2O+M+  (I)where M represents an alkali metal such as lithium, sodium or potassium or combination thereof BHP is the dissociated solution of H2O2 and MOH. In practice, the term BHP typically refers to a solution having 4 molar to 8 molar concentration of perhydroxyl ion (O2H−).
To power the laser, the perhydroxyl ions and alkali ions of the BHP solution are reacted with chlorine gas according to the formula:Cl2+2O2H−+2M+→H2O2+2MCl+O2(1Δ)  (II)The gaseous product stream of reaction II is used as a fuel feed to a COIL laser. The singlet delta oxygen (O2(1Δ)) of the fuel feed is combined with a source of iodine, where the excited state oxygen causes rapid dissociation of the iodine. The iodine atoms, excited by reaction with the singlet delta oxygen, release energy in the form of light. Thus, the excited state iodine is the gain medium for the chemical laser.
A feed containing singlet delta oxygen is utilized as fuel for the laser until the readily usable quantities of O2(1Δ) have been depleted. After being used in the lasing process, the remaining by-products of H2O2, KCl, KOH, and water are recycled to form fresh BHP. Typically, the spent fuel stream will be at a temperature below the freezing point of water. The KCl in the spent fuel, which is only sparingly dissolved below −20° C., is separated from the H2O2 and KOH components of the stream. Water may also be removed from the spent BHP. The liquid stream of H2O2 and KOH is recycled as a fresh BHP stream and combined with chlorine to produce additional singlet delta oxygen. The water and KCl from the spent fuel are heated such that the water melts and dissolves the KCl to form a brine solution. The brine solution may be fed to a chloralkali cell which uses electrolysis to produce KOH, H2, and Cl2.
In practice, the use of recycled KCl solution with a chloralkali cell for use in a COIL system is often less efficient than would be expected. In theory, the operation of the cell should be similar to the sodium based NaCl to NaOH chloroalkali cell which is common in the art of caustic soda production. However, the chloralkali cells which use recycled KCl feeds have been plagued with low levels of conversion, performance degradation, and production rate deterioration. Until now, the problems unique to chloralkali cells used in COIL recycle systems have not been explored. What is needed is a method for improving the performance of chloralkali cells used in COIL systems.